Complex Visual Tasks Reduce People’s Ability to Notice Touch

Royal Holloway psychologists have demonstrated that completing a demanding visual task reduces people’s ability to sense touch. The findings are particularly important given the growing use of tactile information in warning systems – for example, in cars.

The research by Dr Sandra Murphy and Dr Polly Dalton of Royal Holloway, University of London explains why you might not notice your phone vibrating if you are looking for a friend’s face in a crowded place. More alarmingly, you might be more susceptible to pickpocketing when you are searching a complicated departures board for details of your train.

The scientists asked volunteers to perform a letter search task of either low or high difficulty, as well as responding to the presence or absence of a brief vibration delivered simultaneously to either the left or the right hand (50% of trials). Their sensitivity to the clearly noticeable tactile stimulus was reduced when they carried out the more taxing visual search task.

Image shows a man looking at a train departure board.
Royal Holloway research shows that completing a demanding visual task reduces people’s ability to sense touch Image is adapted from the Royal Holloway, University of London press release.

“It was already known that increasing the demands of a visual task could reduce noticing of visual and auditory stimuli.” says Dr Sandra Murphy. “Our research extends this finding to the sense of touch. This is particularly important given the growing use of tactile information in warning systems. For example, some cars now provide tactile alerts when they begin drifting across lanes – our research suggests that drivers will be less likely to notice these alerts when engaging in demanding visual tasks such as searching for directions at a busy junction.”

About this psychology research

Funding: The research, funded by the Economic and Social Research Council.

Source: Royal Holloway, University of London
Image Source: The image is adapted from the Royal Holloway, University of London press release.
Original Research: Abstract for “Out of Touch? Visual Load Induces Inattentional Numbness” by Sandra Murphy and Polly Dalton in Journal of Experimental Psychology: Human Perception and Performance. Published online March 14 2016 doi:10.1037/xhp0000218


Abstract

Out of Touch? Visual Load Induces Inattentional Numbness

It is now well known that the absence of attention can leave people unaware of both visual and auditory stimuli (e.g., Dalton & Fraenkel, 2012; Mack & Rock, 1998). However, the possibility of similar effects within the tactile domain has received much less research. Here, we introduce a new tactile inattention paradigm and use it to test whether tactile awareness depends on the level of perceptual load in a concurrent visual task. Participants performed a visual search task of either low or high perceptual load, as well as responding to the presence or absence of a brief vibration delivered simultaneously to either the left or the right hand (50% of trials). Detection sensitivity to the clearly noticeable tactile stimulus was reduced under high (vs. low) visual perceptual load. These findings provide the first robust demonstration of “inattentional numbness,” as well as demonstrating that this phenomenon can be induced by concurrent visual perceptual load.

“Out of Touch? Visual Load Induces Inattentional Numbness” by Sandra Murphy and Polly Dalton in Journal of Experimental Psychology: Human Perception and Performance. Published online March 14 2016 doi:10.1037/xhp0000218

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